Macrocell/microcell selection schemes based on a new velocity estimation in multitier cellular system

The Intermational Mobile Telecommunications IMT-2000 system uses a microcell concept to provide multimedia services and to support increasing number of users. However, in a microcell system, the number of handoffs is greatly increased. To solve this problem, a multitier cellular structure is proposed, in which high-speed mobile terminals (MTs) are serviced in macrocell and low-speed MTs are serviced in microcell to minimize the number of handoffs. In this system, it is important to precisely estimate the speed of the NIT for the correct selection of the macrocell/microcell. We propose two macrocell/microciell selection schemes based on a new velocity estimation method in a multitier cellular system which uses the sojourn time in a microcell overlapping region. The proposed schemes have various advantages such as good performance when NIT direction is varying, efficient user allocation to cells, quick velocity estimation capability, easy implementation, and low power consumption. We analyze and simulate the conventional and our proposed schemes in the Manhattan cell model, showing the proposed schemes have better performance than the conventional schemes.